In an automobile navigation system described in a patent document 1, when a user tells an operator at a communication center, i.e., an information center about a desired destination on a cellular phone or the like, the operator accesses a database to search for the destination, and transmits accurate positional information on the destination to a navigation device in a vehicle. When the navigation device in the vehicle receives the accurate positional information on the destination, the navigation device designates a destination on the basis of the received accurate positional information on the destination, performs route calculation, and executes route guidance.
Moreover, in a patent document 2, when a road leading to a destination is not found because map data is old, road information on a route from a final guided point to the destination is acquired from a communication center, the route from the final guided point to the destination is calculated, and route guidance is executed.
Patent document 1: JP-A-10-253377 corresponding to U.S. Pat. No. 5,987,381
Patent document 2: JP-A-2006-84256 corresponding to US 2008/0021639
In the case of the constitution described in the patent document 1, when map data to be used by the navigation device in a vehicle is old, a road leading to a destination may not be found. In this case, route guidance may not be executed until the vehicle reaches the destination, or a map may demonstrate that a guided place is different from the place of a desired destination. The constitution cannot therefore be said to be user-friendly. Moreover, in the case of the constitution described in the patent document 2, road information on the route from the final guided point to the destination is merely acquired from the communication center. Therefore, even when a new road is constructed in a zone extending from a current location to the final guided point, the new road cannot be designated as a route.
Thus, it is required to provide a navigation system that even when map data to be used by a navigation device in a vehicle is old, can accurately execute route calculation and route guidance for a route from a current location to a destination.